• Nuclear Engineering and Technology
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• 제48권1호
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• pp.16-25
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• 2016

In severe loss of coolant accidents (LOCA), similar to those experienced at Fukushima Daiichi and Three Mile Island Unit 1, the zirconiumalloy fuel claddingmaterials are rapidlyheateddue to nuclear decay heating and rapid exothermic oxidation of zirconium with steam. This heating causes the cladding to rapidly react with steam, lose strength, burst or collapse, and generate large quantities of hydrogen gas. Although maintaining core cooling remains the highest priority in accident management, an accident tolerant fuel (ATF) design may extend coping and recovery time for operators to restore emergency power, and cooling, and achieve safe shutdown. An ATF is required to possess high resistance to steam oxidation to reduce hydrogen generation and sufficient mechanical strength to maintain fuel rod integrity and core coolability. The initiative undertaken by Electric Power Research Institute (EPRI) is to demonstrate the feasibility of developing an ATF cladding with capability to maintain its integrity in $1,200-1,500^{\circ}C$ steam for at least 24 hours. This ATF cladding utilizes thin-walled Mo-alloys coated with oxidation-resistant surface layers. The basic design consists of a thin-walled Mo alloy structural tube with a metallurgically bonded, oxidation-resistant outer layer. Two options are being investigated: a commercially available iron, chromium, and aluminum alloy with excellent high temperature oxidation resistance, and a Zr alloy with demonstratedcorrosionresistance.Asthese composite claddings will incorporate either no Zr, or thin Zr outer layers, hydrogen generation under severe LOCA conditions will be greatly reduced. Key technical challenges and uncertainties specific to Moalloy fuel cladding include: economic core design, industrial scale fabricability, radiation embrittlement, and corrosion and oxidation resistance during normal operation, transients, and severe accidents. Progress in each aspect has been made and key results are discussed in this document. In addition to assisting plants in meeting Light Water Reactor (LWR) challenges, accident-tolerant Mo-based cladding technologies are expected to be applicable for use in high-temperature helium and molten salt reactor designs, as well as nonnuclear high temperature applications.

• 한국약용작물학회지
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• 제15권6호
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• pp.444-450
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• 2007

Dried leaves from Cedrela sinensis A. Juss. (CS), have been observed to possess various pharmacological activity and contain various antioxidant constituents. The protective effect of ethanol extract of CS on hydrogen peroxide $(H_2O_2)-induced$ neurotoxicity was examined using primary cultured rat cortical neurons in the present study. Exposure of cultured neurons to 100 ${\mu}M\;H_2O_2$ caused a significant neuronal death as assessed by a 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT) assay and Hoechst 33342 staining. The addition of CS, over a concentration range of 10 to $50{\mu}g/m{\ell}$, concentration-dependently prevented the $H_2O_2-induced$ neuronal apoptotic death. CS $(50{\mu}g/m{\ell})$ significantly inhibited $H_2O_2-induced$ elevation of the cytosolic $Ca^{2+}$ concentration $([Ca^{2+}]_c)$, which was measured by a fluorescent dye, Fluo-4 AM. CS (30 and $50{\mu}g/m{\ell})$ inhibited glutamate release and generation of reactive oxygen species (ROS) induced by $100{\mu}M\;H_2O_2$. These results suggest that CS may mitigate the $H_2O_2-induced$ neurotoxiciy by interfering with the increase of $[Ca^{2+}]_c$, and then inhibiting glutamate release and generation of ROS in cultured neurons.

• 산업경영시스템학회지
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• 제38권4호
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• pp.39-44
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• 2015

The VHTR (Very High Temperature gas-cooled nuclear Reactor) has been considered as a major heat source and the most safe generation IV type reactor for mass hydrogen production to prepare for the hydrogen economy era. The VHTR satisfies goals for the GIF (Generation IV International Forum) policy such as sustainablility, economics, reliability and proliferation resistance and physical protection, and safety. As a part of a VHTR economic analysis, we have studied the VHTR construction cost and operation and maintenance cost. However, it is somewhat difficult to expect the ripple effect on the whole industry due to the lack of information about Inter-industries relationship. In many case, the ripple effect are based on experts' knowledge or uncertain qualitative assumptions. As a result, we propose quantitative analysis techniques for ripple effects such as the production inducement effect, added value inducement effect, and employment inducement effect for VHTR 600MWt${\times}$4 modules construction and operation ripple effect based on NOAK (Nth Of A Kind). Because inducement effect values have been published annually, we predict inducement effect's relation function and estimated values including production inducement effect value, added value inducement effect value, and employment inducement effect value using time series and estimated values are verified with published inducement effects' value. This paper presents a new method for the ripple effect and preliminary ripple effect consequence using a time series analysis and inter-industry table. This ripple effect analysis techniques can be applied to effect expectation analysis as well as other type reactor's ripple effect analysis including VHTR for process heat.

• 한국가스학회지
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• 제26권5호
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• pp.49-57
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• 2022

미래에 수소 산업이 활성화되면 LH2 멤브레인 저장탱크 인수기지는 대용량 액화수소를 저장하고 송출할 수 있는 주요한 방안이다. 현재 이러한 인수기지가 존재하지 않기에, 기존 LNG 멤브레인 저장탱크 인수기지 설계 자료를 참고하여 기지 공정모사 모델을 완성하였다. 이 모델을 베이스로 하여 멤브레인 저장탱크 인수기지 운영에서 매우 주요한 인자인 기지 설계조건 변화에 따른 BOG 발생량을 예측하였다. 이를 통하여 LH2 멤브레인 저장탱크 인수기지가 운영될 때를 대비하여 하역시 BOG 발생량을 최소화 할 수 있는 적절한 운전조건을 검토하고자 하였다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.29-32
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• 2008

Testing was conducted to determine the performance of a residential fuel cell system when subjected to DSS and WSS operation, especially for start-up and shut-down characteristics. In terms of start-up time, it took about 70min to start output power generation and stably to reach 1kW at cold start. Measurement of the characteristics of heat and power generation were carried out at start-up and shut-down time. Fuel gas is used for heating both reformer and stack from start-up to the beginning of power generation. In terms of start-up and shut-down characteristics, it was important to control the reformer temperature precisely. The average output water temperature during the rated output operation(960W) was $63.2^{\circ}C$ constantly. The results of the investigation are being used to develop a new test protocols for residential fuel cell system.

• 전기학회논문지
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• 제65권11호
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• pp.1925-1930
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• 2016

Fuel cell power generation system, unlike conventional energy sources, converts chemical energy into electrical energy through electrochemical reaction of hydrogen and oxygen. This paper presents the control of interleaved multi-phase boost converter as the feasibility study on small-scale prototype electric railway vehicle application using fuel cell generation system. PSIM simulation program is to be used to implement the modeling of the electrical fuelcell as well as traction motor control with interleaved multi-phase boost converter. Comparing the input current ripple rate, two-phase interleaved boost converter is less than the boost converter. But the more multi-phase not less proportional to the ripple factor. we confirmed that the amplitude of the input current ripple rate of converter depend on duty ratio.

• 한국항해항만학회지
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• 제44권4호
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• pp.283-290
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• 2020

액화 수소 운반선에서 증발가스의 발생은 불가피하며, 화물탱크 내부의 압력 문제를 피하기 위해 적절한 조치가 필요하다. 이 증발 가스는 선박의 추진연료로 사용 될 수 있으며, 추진에 사용되고 남은 나머지 부분은 재액화 또는 연소시키는 등 효과적으로 관리해야 한다. 본 연구에서는 수소 추진 시스템을 갖춘 160,000㎥ 액화 수소 운반선에 최적화된 증발 가스 재액화 시스템을 제안한다. 이 시스템은 수소 압축 및 헬륨 냉매 섹션으로 구성되고, 화물탱크로부터 배출되는 증발가스의 냉열을 효과적으로 활용하여 효율을 증가시켰다. 본 연구에서는 공급 온도 -220℃인 수소 증발가스가 재액화 시스템에 들어가는 상태에서 증발가스의 재액화 비율에 따른 엑서지 효율 및 에너지 소모율 (SEC, Specific Energy Consumption) 분석을 통해 시스템을 평가하였다. 그 결과 재액화 비율 20%에서 4.11kWh/kgLH₂의 SEC와 60.1%의 엑서지 효율을 보여 주었다. 아울러, 수소 압축압력, 수소 팽창기의 입구온도, 공급 증발가스 온도변화에 따른 영향을 확인하였다.

• 한국수소및신에너지학회논문집
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• 제23권4호
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• pp.390-396
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• 2012

In order to understand the nature of dendritic zinc growth, electrochemical zinc redox reaction on nickel plate was investigated in aqueous solutions containing different concentrations, 0.2, 0.1 and 0.02 $mol{\cdot}dm^{-3}$ (M), of zinc sulfate ($ZnSO_4$) or zinc chloride ($ZnCl_2$). Zinc ion was efficiently reduced and oxidized on nickel in the high-concentration (0.2 M) solution, whereas relatively poor efficiency was obtained from the other low-concentration solutions (0,1 and 0.02 M). Cyclic voltammetry (CV) analysis revealed that the 0.2 M electrolyte solution decomposes at more positive potentials than the 0.1 and the 0.02 M solutions. These results suggested that the concentration of electrolyte solution and anion would be an important factor that suppresses the reaction of the zinc dendrite formation. Scanning Electron Microscopy (SEM) data revealed that the shape of dendritic zinc and its growing behavior were also influenced by electrolyte concentration.

• Macromolecular Research
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• 제16권2호
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• pp.113-119
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• 2008

A series of amphiphilic dendrons n-18 (n: generation number, 18: octadecyl chain) based on an aliphatic polyether denderitic core and octadecyl peripheries were synthesized using a convergent dendron synthesis consisting of a Williamson etherification and hydroboration/oxidation reactions. This study investigated their thermal and self-assembling behavior in the solid state using differential scanning calorimetry (DSC), Fourier transform infrared (FT-IR) absorption spectroscopy, and small angle X-ray scattering (SAXS). DSC indicated that the melting transition and the corresponding heat of the fusion of the octadecyl chain decreased with each generation. FT-IR showed that the hydroxyl focal groups were hydrogen-bonded with one another in the solid state. DSC and FT-IR indicated microphase-separation between the hydrophilic dendritic cores and hydrophobic octadecyl peripheries. SAXS data analysis in the solid state suggested that the lower-generation dendrons 1-18 and 2-18 self-assemble into lamellar structures based upon a bilayered packing of octadecyl peripheries. In contrast, the analyzed data of higher-generation dendron 3-18 is consistent with 2-D oblique columnar structures, which presumably consist of elliptical cross sections. The data obtained could be rationalized by microphase-separation between the hydrophilic dendritic core and hydrophobic octadecyl peripheries, and the degree of interfacial curvature associated with dendron generation.

• 한국수소및신에너지학회논문집
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• 제18권3호
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• pp.230-237
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• 2007

알칼리 수열합성법에 의해 높은 비표면적을 갖는 티타니아 나노튜브(TiNT)를 합성하였다. 가시광용 광촉매로서의 응용성을 조사하기 위해 CdS 나노입자와 조성(r=TiNT/(CdS+TiNT))을 바꿔가며 일련의 무기 복합필름을 제조하였다. 또한 비교를 위해 티타니아 나노튜브 대신 티타니아 나노입자와 CdS로 구성된 복합체를 역시 제조하였다. 합성된 티타니아 나노튜브는 $200^{\circ}C$ 이상의 소결온도에서 부분적으로 튜브 구조의 붕괴가 시작되었지만, CdS와의 복합체는 $450^{\circ}C$ 까지도 비교적 안정한 구조를 유지하였다. (CdS+TiNT)복합필름은 티타니아 나노입자 복합계와 비교할 때 가시광 흡수 측면에서는 유사한 정도를 나타내었지만, 수소생산 활성과 광전류 발생은 오히려 훨씬 낮은 값을 나타내었다. 결과적으로, 티타니아 나노튜브는 그의 높은 비표면적에도 불구하고 자기들끼리의 응집성이 강하여 CdS와의 전기적 상호작용이 약하며, 특히 얇은 튜브벽 두께(${\sim}3nm$)와 낮은 결정성에 기인하는 약한 광전류 특성은 이의 광촉매로서의 응용성을 상당히 제한하는 요소로 나타났다.